KR100518223B1 - Method of forming mask pattern for diminishing radial error - Google Patents

Abstract

The present invention relates to a method for minimizing a radial error in a mask pattern forming method.

The present invention includes extracting a radial error in a mask pattern forming process, dividing the radial error into a plurality of mask pattern regions according to the extracted data, and changing a plurality of mask pattern sizes to correct the radial error. .

In addition, the present invention extracts a radial error in the process of forming a mask pattern, using the extracted data divided into a plurality of pattern areas, and by configuring a pattern file corresponding to the plurality of pattern areas, the pattern file And exposing by varying the energy of the light source.

In addition, the present invention extracts a radial error in the mask pattern forming process, and using the extracted data to form a pattern file by dividing into a plurality of pattern regions, the edge region far from the mask center of the pattern region Exposing a light source according to a pattern file corresponding to the light source; and exposing the reactive light source to the entire mask.

Description

Mask pattern formation method to reduce radial error {METHOD OF FORMING MASK PATTERN FOR DIMINISHING RADIAL ERROR}

The present invention relates to a method of forming a mask pattern, and more particularly, to vary the pattern size of a mask layout, to control the energy of an electron beam, or to form a mask pattern using a ghost method. It relates to a method for minimizing the radial error shown in.

In recent years, as the degree of integration of semiconductor devices increases, the demand for precision of each part constituting the semiconductor is increasing. Among them, in forming a mask, it is important to form an accurate mask pattern without errors.

The method of forming the mask pattern is a spin spray method, in which a reaction solution for growing or etching at a low speed or a stationary state is sprayed, and then the reaction solution is spread evenly throughout the mask at a high speed rotation.

1 illustrates a conventional mask pattern. In FIG. 1, the mask pattern shows the case where it has the same level of 5x5.

In the case of forming the mask pattern as described above, the spin spray method is also used in the blank mask PR coating, and the thickness of the PR is increased because the position of the nozzle spraying the reaction solution is concentrated in the middle of the mask. It varies in proportion to the distance from the middle. In particular, the PR thickness specifications provided by the blank mask makers are also provided in a circular shape with no direction.

When the mask pattern is grown, the reaction solution is spread by the high-speed rotation, and the reaction solution is reacted in a fresh state at the center part, but the farther it is from the center, the fresher the reaction solution is, the worse the freshness is. Decreases the ability to do so. Therefore, the reaction liquid weakened in reaction force requires more time to react, but the farther it is from the center, the weaker the centripetal force is, so that the reaction liquid leaves the mask at a higher speed. As a result, the reaction time is also reduced in a weak reaction force, and an error occurs in a certain form from the center of the mask, thereby reducing the accuracy of the critical dimension (CD) in the wafer exposure process and making the process difficult. Weak process margin.

The mask pattern in the case where the radial error by the spin spray method as described above is shown in FIG. Referring to Figure 2, it can be seen that a certain type of error occurs according to the distance from the center. This error is called a radial error because it occurs in proportion to the distance from the center.

In order to reduce the radial error, a pattern may be formed by injecting the reaction solution together not only in the center but also at a certain distance from the center in the process of injecting the reaction solution into the mask. By separately injecting, there is a concern that the mask pattern may be irregularly formed, and economical difficulty also occurs in terms of equipment because the reaction liquid injection nozzle must be further configured.

The present invention is to solve the above problems, to provide a method of reducing the radial error by varying the size of the mask pattern in the mask growth or etching process, controlling the energy of the electron beam, or using a ghost method. There is a purpose.

In order to achieve the above object, the mask pattern forming method of the present invention comprises the steps of extracting a radial error, divided into a plurality of mask patterns according to the extracted error, and the size of the mask pattern according to the plurality of patterns identified above Characterized in that it comprises a step of forming a layout by different.

The mask pattern is characterized in that to increase the size of the portion where the radial error is large.

The plurality of mask patterns may be divided into polygons in order to minimize a change in the vicinity of a boundary divided by an exposure method.

In addition, the present invention includes a method for calculating the energy to compensate for the radial error from the center of the mask in accordance with the distance, by configuring a plurality of pattern files to vary the energy of the light source according to the corresponding area to expose It is done.

The plurality of pattern files may be divided into polygons according to an exposure method.

In addition, the present invention is characterized in that it comprises an exposure step of exposing the light source only to the edge region distant from the center of the mask, and again exposing the light source to the entire mask.

The light source exposed to the edge region may be exposed by defocusing.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Errors in the process of forming the mask pattern can be roughly divided into radial errors, side-to-side errors, and random errors.

Radial error is an error that occurs in proportion to the distance according to the reaction rate of the reaction solution due to the high-speed rotation of the mask, and the side-to-side error is one side and the opposite side because the mask is not completely flat. It is an error that appears in between, and the remaining errors other than the radial error and the side-to-side error are divided into random errors.

For example, a mask pattern is formed by using an array of 11 × 11 in order to extract a radial error occurring in the mask pattern. In the case of FIG. 3, when the reaction solution is injected with a target of 1,500 and the mask is rotated at a high speed to form a mask pattern, the distribution of the pattern is shown.

In order to three-dimensionally confirm the distribution shown in Figure 3 is shown in a three-dimensional screen in Figure 5a.

In the mask pattern formed as described above, the average of each data value is 1,574. At this time, a total error is calculated based on the average value 1,574 and the data distribution is shown as in FIG. 4A. 4A illustrates a distribution of values obtained by subtracting an average value 1,574 from each data value formed on a mask pattern.

Radial error is extracted using the total error value shown in FIG. 4A. In the pattern having the arrangement of 11 × 11, four data values at the same distance with respect to the center are added, and the average value of the values is a radial error value shown in FIG. 4B. For example, considering the total error value at the outermost corner in FIG. 4A, -31 in the upper left, -62 in the upper right, -44 in the lower right, and -14 in the lower left are equal distances from the center, respectively. It is the error value of, which is added to find the average and becomes -38. When the radial error value thus obtained is displayed in an area at the same distance from the center, a distribution diagram as shown in FIG. 4B is obtained. In the above, since the error appearing in the actual mask pattern formation process is taken into account, there is a slight difference from the value of the simple numerical calculation.

The distribution of the radial error of FIG. 4B is shown in FIG. Referring to FIG. 5B, it can be seen at a glance that an error increases while spreading concentrically from the center of the pattern forming the 11 × 11 array.

FIG. 4C illustrates a distribution diagram of side-to-side error values extracted by considering an error appearing in an actual mask pattern forming process from the difference between the total error and the radial error. In FIG. 5C, the distribution diagram of FIG. 4C is illustrated in three dimensions, and the lower left side of the mask is inclined upward and the upper right side is inclined downward. Such a side-to-side error appears in the mask fabrication equipment and is a problem to be considered in the fabrication process of the equipment, not the mask pattern formation method.

In the total error of FIG. 4A, the remaining errors except for the radial error of FIG. 4B and the side-to-side error of FIG. 4C are shown as random errors in FIG. 4D.

The present invention proposes a mask pattern forming method as follows to minimize the radial error as described above.

First, the pattern size is changed according to the distance on the mask layout using the radial error data obtained above.

FIG. 6 illustrates a mask pattern formed by changing a pattern size to compensate for the radial error shown in FIG. 2. The size of the mask pattern is determined in consideration of the data conversion method of the exposure equipment, the size of the exposure beam, the writing method, and the like. Since the reactivity of the outer portion of the mask is reduced due to a radial error, FIG. 6 illustrates a case in which the pattern size of the outer portion is increased.

In this case, it is preferable to divide the pattern size into a polygonal shape in order to minimize the change in the vicinity of the boundary according to the exposure method used in the mask fabrication process.

As described above, the method of changing the pattern size in the layout of the mask requires only one pattern file for forming a pattern, and has the advantage of exposing the same energy for the entire mask area.

The second method is a method in which the energy of the light source exposed through the mask is differently exposed according to the radial error after the reaction solution is injected.

As shown in FIG. 7, a region of several masks is divided according to a radial error, and a pattern file having an energy value of a light source to be exposed is formed in each region to be exposed at different energies, thereby compensating for errors occurring in the mask pattern. . At this time, the exposure energy value for each region can use the energy table used in the conventional mask pattern forming method. FIG. 7 illustrates a case in which a mask pattern is formed by dividing the mask into two parts, a center region and an outer region of the mask to increase exposure energy of the outer region.

As described above, in the case of forming the mask pattern by varying the exposure energy, it is preferable to divide the mask area in the form of a polygon for the same reason as the first method.

The third method is a ghost method in which a defocused light source is first exposed to the outside where a large radial error appears on the mask, and then the reactive light source is again exposed to the entire mask.

Referring to FIG. 8, in order to compensate for an error corresponding to a difference between the center region and the outer region, the defocused light source is first exposed to the outer region. The exposed defocused light source does not generate a reaction on the mask, but increases the energy of the outer portion to a certain level. After that, when the reactive light source is exposed to the entire mask, the center region reacts with the energy corresponding to the reactive light source, but the outer region is centered by the sum of the energy formed by the defocused light source and the energy by the reactive light source. This compensates for radial errors with the area.

The above ghost method exposes the outer area of the mask twice, but does not change the overall mask design, and thus does not cause alignment problems caused by changing or dividing the data. have.

Since the three methods described above can be applied to both the process of growing the pattern on the mask and the etching process in the mask fabrication process, the efficiency of the fabrication process can be greatly increased.

As described in detail above, according to the mask pattern forming method of the present invention, the process margin may be improved by minimizing a radial error occurring in the process of forming the mask pattern.

In addition, the present invention can be applied economically without changing the equipment used in the conventional mask pattern forming method has the advantage of reducing the cost economically.

Hereinafter, this invention can be implemented in various changes in the range which does not deviate from the summary.

1 is a view showing a conventional mask pattern,

2 is a view illustrating a mask in which a pattern is formed by a spin spray method;

3 is a data distribution diagram of a mask pattern formed by a spin spray method in order to measure a radial error;

4A is a distribution diagram of total error extracted by the data distribution of FIG. 3;

4B is a distribution diagram of the radial error extracted by the data distribution of FIG. 3;

4C is a distribution diagram of side-to-side error extracted by the data distribution of FIG. 3,

4D is a distribution diagram of random errors extracted by the data distribution of FIG. 3;

5A is a three-dimensional distribution diagram of the data of FIG. 3;

5B is a three-dimensional distribution diagram of the radial error of FIG. 4B;

5C is a three-dimensional distribution diagram of the side-to-side error of FIG. 4C;

6 is a view when a mask pattern is formed by changing a pattern size according to an embodiment of the present invention;

7 is a view showing a mask in the case of forming a pattern by varying the energy of the electron beam according to an embodiment of the present invention,

8 illustrates a mask in which a pattern is formed using a ghost method according to an embodiment of the present invention.

Claims (9)

Extracting a radial error in a mask pattern forming process and dividing the radial error into a plurality of mask pattern regions according to the extracted data; And changing a plurality of mask pattern sizes to correct the radial error. The method of claim 1, wherein the plurality of mask patterns are A mask pattern forming method, characterized in that divided into a polygonal form to minimize the instantaneous change in the vicinity of the boundary of the pattern area divided into a plurality. The method of claim 1, wherein the mask pattern is A method of forming a mask pattern, wherein the pattern size of an outer region having a large radial error is increased away from the mask center. Extracting a radial error in a mask pattern forming process and dividing the radial error into a plurality of pattern regions by using the extracted data; And forming a pattern file corresponding to the plurality of pattern regions, and exposing by varying the energy of the light source according to the pattern file. The method of claim 4, wherein the plurality of pattern areas A mask pattern forming method, characterized in that divided into a polygonal form to minimize the instantaneous change in the vicinity of the boundary of the pattern area divided into a plurality. The method of claim 4, wherein the light source energy is A mask pattern forming method characterized by increasing the light source energy in a region with weak reactivity to expose it. Extracting a radial error in a mask pattern forming process and dividing the radial error into a plurality of pattern regions to form a pattern file, respectively; Exposing a light source according to a pattern file corresponding to an edge region far from a mask center among the pattern regions; And exposing a reactive light source to the entire mask. The method of claim 7, wherein the plurality of pattern areas A mask pattern forming method, characterized in that divided into a polygonal form to minimize the instantaneous change in the vicinity of the boundary of the pattern area divided into a plurality. 8. The method of claim 7, wherein exposing the light source to an edge region of the mask A mask pattern forming method characterized by using a defocus light source.